Preparation Method and Application of 3D Printed Silica Composite Aerogel Component

Abstract

Preparation method and application of 3D printed silica composite aerogel component, belonging to the technical field of aerogel preparation. Mix a silica precursor solution, a silica gel slurry and a montmorillonite colloid solution in a certain proportion, and stir until a uniform precursor wet gel suitable for direct writing 3D printing is obtained. Transfer the precursor wet gel to an ink writer and install it on a 3D printer to directly write and print a 3D wet gel component. Under an ammonia atmosphere, the wet gel component is further cured, and through ethanol exchange and supercritical drying, a 3D aerogel component is obtained. In the present invention, the preparation of the 3D printed aerogel is simple and has good forming.

Description

Technical Field

[0001] The present invention relates to silica gel, and particularly to a preparation method and application of a 3D printed silica composite aerogel component, belonging to the field of chemical technology. Background Art

[0002] Aerogel is a mesoporous sol-gel material with a high specific surface area (500 - 1000 m 2 / g), low density (0.001 - 0.200 g −1 / cm −3 ), and extremely low thermal conductivity (as low as 12 mW / (m•K)). The heat insulation effect of aerogel composite thermal insulation materials is more than 3 times better than that of conventional thermal insulation materials, so they are called super thermal insulation materials. Aerogel composite thermal insulation materials are widely used in various fields such as civil, industrial, military, and aerospace. Specific practical examples include: petrochemical pipelines; heat insulation sheets on the outer surface of space shuttles; heat insulation felts for the Spirit Mars rover; collectors for the Stardust space probe; heat shield structural materials for aircraft engines, etc. As an efficient thermal insulation material, aerogel composite thermal insulation materials are widely used in civil fields such as thermal pipelines, chemical engineering, metallurgy, industrial furnaces, and shipbuilding. Aerogel can greatly save energy, and the development of this technology is of great significance for improving the industrial level and building a green economy.

[0003] Silica aerogel is the most studied and used type of aerogel in this field so far. Although aerogels can have extremely high strength-to-weight ratios, silica aerogels are usually brittle and difficult to be shaped by cutting and processing. 3D printing provides an alternative way for easy shaping and processing of aerogels. Especially for special-shaped aerogel components with special structures, 3D printing can form them in one step. The feasibility of 3D printing aerogels of graphene oxide and cellulose has been confirmed, but it is a great challenge for silica aerogels. A recent study reported a preparation method for 3D printed silica aerogels (Zhao et al. Nature 2020, 584 , 387). However, this method requires the use of a large amount of organic or polymer reagents as thixotropic agents and anti-settling agents for the precursor gel, such as polyethoxydisiloxane, pentanol, and polypropylene glycol bis(2-aminopropyl) ether. This method not only has poor environmental friendliness and cumbersome steps, but the subsequent polymers remaining in the aerogel material may cause poor temperature stability and reduced heat insulation. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method and application of a 3D printed silica composite aerogel component.

[0005] To achieve the object of the present invention, the following technical solutions are adopted: A preparation method of a 3D printed silica composite aerogel member, comprising the following steps:

[0006] S1: Preparation of a silica precursor solution, which is prepared by hydrolyzing tetraethyl orthosilicate in a solvent mixture of water, acid and ethanol; the pH value of the solvent mixture of water, acid and ethanol is 4-6;

[0007] S2: Take a part of the silica precursor solution obtained in step S1, add ammonia water to form a gel, and crush the gel into silica slurry;

[0008] S3: Dissolve montmorillonite in water to obtain a montmorillonite colloidal solution;

[0009] S4: Mix and stir evenly the silica precursor solution prepared in step S1, the silica slurry prepared in step S2, and the montmorillonite colloidal solution prepared in step S3 to obtain a precursor wet gel for 3D printing;

[0010] S5: Transfer the precursor wet gel obtained in step S4 to an ink writer, install it on a 3D printer, and perform direct writing printing to obtain a 3D wet gel member;

[0011] S6: Place the 3D wet gel member obtained in step S5 in an ammonia atmosphere for further curing, and age it to obtain a 3D hardened gel member;

[0012] S7: Immerse the 3D hardened gel member obtained in step S6 in an organic solvent to obtain a 3D organic gel member;

[0013] S8: Dry the 3D organic gel member obtained in step S7 to obtain a 3D printed silica composite aerogel member.

[0014] Furthermore; the silica precursor solution in step S1 is prepared by hydrolyzing tetraethyl orthosilicate in a mixed solvent formed by an acid solution and ethanol, and the mass ratio in the mixed solution is: tetraethyl orthosilicate: acid solution: absolute ethanol = 1: 2-20: 2-20, the pH is 4-6, and the acid is hydrochloric acid or nitric acid or acetic acid.

[0015] Furthermore; the silica gel slurry in step S2 is crushed silica gel particles, and the particle size of the silica gel particles is 1-100 microns.

[0016] Furthermore; the montmorillonite colloidal solution in step S3 is prepared by dispersing montmorillonite in water and stirring for 2-8 hours; the concentration of the montmorillonite colloidal solution is 1-10 wt%.

[0017] Further, the mass ratio of the silica precursor solution, the silica gel slurry, and the montmorillonite colloid solution mixed in step S4 is 1:0.5 - 2:0.5 - 2.

[0018] Further, the ammonia gas in step S6 is generated by the volatilization of concentrated ammonia water under a closed condition, the concentration of the ammonia water is 1 - 14 mol / L; the aging time is 2 - 8 hours.

[0019] Further, the soaking time in step S7 is 6 - 8 h, and the organic solvent is anhydrous ethanol or methanol or acetone solution.

[0020] Further, the drying method in step S8 is supercritical carbon dioxide drying or supercritical ethanol drying.

[0021] Application of the 3D - printed silica composite aerogel component, and the 3D - printed silica composite aerogel component is used for heat - insulating materials.

[0022] The beneficial effects of the present invention are as follows: (1) The preparation method of the present invention is simple and reliable. The raw material montmorillonite is derived from natural minerals and can be used as a thixotropic agent and anti - settling agent for the 3D - printed precursor composite gel; the preparation of silica gel particles is simple and can be used as a thixotropic agent and cross - linker for the 3D - printed precursor composite gel. (2) The 3D - printed aerogel component prepared by the present invention is a pure inorganic material, avoiding the influence of inorganic residues caused by the use of organic polymers on the thermal stability and thermal conductivity of the aerogel. (3) Due to the use of 3D printing, the aerogel structure is excellent, with high resolution, facilitating the one - step forming process of components required for small devices. (4) The thermal conductivity (16.5 mW / (m·K)) of the 3D - printed aerogel component prepared by the present invention under environmental conditions is lower than that of air, having great application prospects in the field of thermal insulation. Description of the Drawings

[0023] Figure 1 This is a photo of the 3D - printed silica composite aerogel component prepared by the present invention.

[0024] Figure 2 This is a scanning electron microscope image of the 3D - printed silica composite aerogel component prepared by the present invention. Detailed Embodiments

[0025] To further illustrate the present invention, the present invention will be described in detail below with reference to the embodiments, but they cannot be construed as limiting the protection scope of the present invention. Embodiment 1

[0026] Mix 20.0 g of absolute ethanol and 20.0 g of dilute acid (pH 4.0) and stir evenly, then add 10.0 g of tetraethyl orthosilicate and stir for hydrolysis to obtain a silica precursor solution. Take 10 g of the above silica gel precursor solution, add 1.0 mol / L ammonia water dropwise to form a gel, and crush it into a silica gel slurry as a thixotropic regulator and crosslinking agent. Additionally, add 10 g of montmorillonite to 200 g of pure water and stir for 6 hours until a uniform and viscous colloidal solution is obtained as an anti-settling agent and thixotropic regulator. Take 10 g of the above silica precursor solution, 10 g of silica gel slurry, and 10 g of montmorillonite colloidal solution, mix and stir evenly to obtain a 3D printing precursor wet gel with thixotropic behavior. Store the precursor wet gel in a 4°C refrigerator for later use.

[0027] Take 15 g of the above precursor wet gel, transfer it to an ink writer with a capacity of 20 mL and a nozzle diameter of 0.4 mm, and install it on a 3D printer. Under the assistance of a computer program, through direct writing printing, a 3D wet gel component with a certain geometric configuration is obtained. In a closed space, place the component beside an open beaker containing 3.0 mol / L ammonia water. Ammonia gas escapes from the beaker and penetrates into the 3D wet gel component, further triggering the crosslinking and hardening of the silica precursor solution. After standing for 4 hours for aging, take out the 3D hardened gel component, exchange it 3 times in absolute ethanol, 8 hours each time, to obtain a 3D hardened alcohol gel component. Subject the obtained alcohol gel to supercritical liquid carbon dioxide drying treatment to obtain the final 3D printed silica composite aerogel component. Example 2

[0028] Mix 30.0 g of absolute ethanol and 50.0 g of dilute acid (pH 5.0) and stir evenly, then add 10.0 g of tetraethyl orthosilicate and stir for hydrolysis to obtain a silica precursor solution. Take 10 g of the above silica gel precursor solution, add 2.0 mol / L ammonia water dropwise to form a gel, and crush it into a silica gel slurry as a thixotropic regulator and crosslinking agent. Additionally, add 15.0 g of montmorillonite to 200 g of pure water and stir for 8 hours until a uniform and viscous colloidal solution is obtained as an anti-settling agent and thixotropic regulator. Take 10 g of the above silica precursor solution, 5.0 g of silica gel slurry, and 10.0 g of montmorillonite colloidal solution, mix and stir evenly to obtain a 3D printing precursor wet gel with thixotropic behavior. Store the precursor wet gel in a 4°C refrigerator for later use.

[0029] Take 10 g of the above-mentioned precursor wet gel, transfer it to an ink writer with a capacity of 10 mL and a nozzle diameter of 0.5 mm, and install it on a 3D printer. With the assistance of a computer program, through direct writing printing, a 3D wet gel component with a certain geometric configuration is obtained. In a closed space, the component is placed beside an open beaker containing 3.0 mol / L ammonia water. Ammonia gas escapes from the beaker and penetrates into the 3D wet gel component, further triggering the cross-linking and hardening of the silica precursor solution. After standing for 4 hours for aging, the 3D hardened gel component is taken out and exchanged 3 times in absolute ethanol, 8 hours each time, to obtain a 3D hardened alcohol gel component. The obtained alcohol gel is subjected to supercritical liquid carbon dioxide drying treatment to obtain the final 3D printed silica composite aerogel component. Example 3

[0030] Mix 40.0 g of absolute ethanol and 30.0 g of dilute acid (pH 5.0) and stir evenly, then add 10.0 g of tetraethyl orthosilicate and stir for hydrolysis to obtain a silica precursor solution. Take 10 g of the above silica precursor solution, add 2.0 mol / L ammonia water to form a gel, and crush it into a silica gel slurry as a thixotropic regulator and cross-linking agent. In addition, add 20.0 g of montmorillonite to 200 g of pure water and stir for 8 hours until a uniform viscous colloidal solution is obtained as an anti-settling agent and thixotropic regulator. Take 10 g of the above silica precursor solution, 8.0 g of silica gel slurry, and mix and stir evenly with 15.0 g of montmorillonite colloidal solution to obtain a 3D printing precursor wet gel with thixotropic behavior. The precursor wet gel is stored in a refrigerator at 4°C for later use.

[0031] Take 10 g of the above-mentioned precursor wet gel, transfer it to an ink writer with a capacity of 20 mL and a nozzle diameter of 1.0 mm, and install it on a 3D printer. With the assistance of a computer program, through direct writing printing, a 3D wet gel component with a certain geometric configuration is obtained. In a closed space, the component is placed beside an open beaker containing 4.0 mol / L ammonia water. Ammonia gas escapes from the beaker and penetrates into the 3D wet gel component, further triggering the cross-linking and hardening of the silica precursor solution. After standing for 4 hours for aging, the 3D hardened gel component is taken out and exchanged 3 times in absolute ethanol, 8 hours each time, to obtain a 3D hardened alcohol gel component. The obtained alcohol gel is subjected to supercritical liquid carbon dioxide drying treatment to obtain the final 3D printed silica composite aerogel component. Example 4

[0032] Mix 20.0 g of absolute ethanol and 40.0 g of dilute acid (pH = 6.0) and stir evenly, then add 10.0 g of tetraethyl orthosilicate and stir for hydrolysis to obtain a silica precursor solution. Take 10 g of the above silica gel precursor solution, add 2.0 mol / L ammonia water dropwise to form a gel, and crush it into a silica gel slurry as a thixotropic regulator and crosslinking agent. Additionally, add 15.0 g of montmorillonite to 200 g of pure water and stir for 6 hours until a uniform viscous colloidal solution is obtained as an anti-settling agent and thixotropic regulator. Take 10 g of the above silica precursor solution, 10.0 g of silica gel slurry, and mix and stir evenly with 15.0 g of montmorillonite colloidal solution to obtain a 3D printing precursor wet gel with thixotropic behavior. Place the precursor wet gel in a 4°C refrigerator for storage and use.

[0033] Take 10 g of the above precursor wet gel, transfer it to an ink writer with a capacity of 15 mL and a nozzle diameter of 2.0 mm, and install it on a 3D printer. With the assistance of a computer program, through direct writing printing, a 3D wet gel component with a certain geometric configuration is obtained. In a closed space, place the component beside an open beaker containing 5.0 mol / L ammonia water. Ammonia gas escapes from the beaker and penetrates into the 3D wet gel component, further triggering the crosslinking and hardening of the silica precursor solution. After standing for 4 hours for aging, take out the 3D hardened gel component, exchange it 3 times in absolute ethanol, 8 hours each time, to obtain a 3D hardened alcohol gel component. Subject the obtained alcohol gel to supercritical liquid carbon dioxide drying treatment to obtain the final 3D printed silica composite aerogel component. Example 5

[0034] Mix 30.0 g of absolute ethanol and 50.0 g of dilute acid (pH = 6.0) and stir evenly, then add 10.0 g of tetraethyl orthosilicate and stir for hydrolysis to obtain a silica precursor solution. Take 10 g of the above silica gel precursor solution, add 2.0 mol / L ammonia water dropwise to form a gel, and crush it into a silica gel slurry as a thixotropic regulator and crosslinking agent. Additionally, add 10.0 g of montmorillonite to 200 g of pure water and stir for 6 hours until a uniform viscous colloidal solution is obtained as an anti-settling agent and thixotropic regulator. Take 10 g of the above silica precursor solution, 20.0 g of silica gel slurry, and mix and stir evenly with 20.0 g of montmorillonite colloidal solution to obtain a 3D printing precursor wet gel with thixotropic behavior. Place the precursor wet gel in a 4°C refrigerator for storage and use.

[0035] Take 10 g of the above-mentioned precursor wet gel, transfer it to an ink writer with a capacity of 15 mL and a nozzle diameter of 0.5 mm, and install it on a 3D printer. With the assistance of a computer program, through direct writing printing, a 3D wet gel component with a certain geometric configuration is obtained. In a closed space, the component is placed beside an open beaker containing 2.0 mol / L ammonia water. Ammonia gas escapes from the beaker and penetrates into the 3D wet gel component, further triggering the cross-linking and hardening of the silica precursor solution. After standing for 4 hours for aging, the 3D hardened gel component is taken out and exchanged 3 times in absolute ethanol, 8 hours each time, to obtain a 3D hardened alcohol gel component. The obtained alcohol gel is subjected to supercritical liquid carbon dioxide drying treatment to obtain the final 3D printed silica composite aerogel component.

[0036] The thermal conductivity of the aerogels obtained from the above 5 examples was tested, and the thermal conductivity was ~16.5 mW / (m·K), which is lower than the thermal conductivity of air under ambient conditions (25 mW / (m·K)). Therefore, the aerogels prepared by the present invention also have great application prospects in the field of thermal insulation.

[0037] Figure 1 This is a photograph of the 3D printed composite aerogel component prepared by the present invention. It can be seen from the figure that the 3D printed composite aerogel component prepared by the present invention is a grid-like three-dimensional self-supporting structure, which can meet the personalized customization of special-shaped structural components and overcome the difficulty that silica aerogel cannot be cut due to its brittleness.

[0038] Figure 2 This is a scanning electron microscope image of the 3D printed composite aerogel component prepared by the present invention. It can be seen from the figure that the grid-like structure of the 3D printed composite aerogel is uniform, the diameter of the gel ejected by the 3D printing nozzle is about 0.4 mm, and the morphology is uniform and smooth, showing the advantages of 3D printed composite aerogel in personalized customization.

[0039] Repeating the above examples multiple times, the obtained results are similar, indicating that the preparation method of this method has good repeatability.

[0040] Although the above examples have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. Preparation method of 3D printed silica composite aerogel component, characterized in that It includes the following steps: S1: Preparation of the silica precursor solution, which is obtained by hydrolyzing tetraethyl orthosilicate in a solvent mixture of water, acid, and ethanol; the pH value of the solvent mixture of water, acid, and ethanol is 4 - 6; S2: Take a part of the silica precursor solution obtained in step S1, add ammonia water to form a gel, and crush the gel into silica slurry; S3: Dissolve montmorillonite in water to obtain a montmorillonite colloidal solution; S4: Mix and stir evenly the silica precursor solution prepared in step S1, the silica slurry prepared in step S2, and the montmorillonite colloidal solution prepared in step S3 to obtain a precursor wet gel for 3D printing; S5: Transfer the precursor wet gel obtained in step S4 to an ink writer, install it on a 3D printer, and perform direct writing printing to obtain a 3D wet gel component; S6: Place the 3D wet gel component obtained in step S5 in an ammonia atmosphere for further curing, and age it to obtain a 3D hardened gel component; S7: Immerse the 3D hardened gel component obtained in step S6 in an organic solvent to obtain a 3D organic gel component; S8: Dry the 3D organic gel component obtained in step S7 to obtain a 3D printed silica composite aerogel component.

2. The preparation method according to claim 1, characterized in that: In step S1, the silica precursor solution is obtained by hydrolyzing tetraethyl orthosilicate in a mixed solvent formed by an acid solution and ethanol. The mass ratio in the mixed solution is: tetraethyl orthosilicate : acid solution : absolute ethanol = 1 : 2 - 20 : 2 - 20, the pH is 4 - 6, and the acid is hydrochloric acid or nitric acid or acetic acid.

3. The preparation method of the 3D printed silica composite aerogel component according to claim 1, characterized in that: In step S2, the silica gel slurry is the crushed silica gel particles, and the particle size of the silica gel particles is 1 - 100 microns.

4. The preparation method according to claim 1, wherein: In step S3, the montmorillonite colloidal solution is obtained by dispersing montmorillonite in water and stirring for 2 - 8 hours; the concentration of the montmorillonite colloidal solution is 1 - 10 wt%.

5. The preparation method according to claim 1, characterized in that: In step S4, the mass ratio of the silica precursor solution, silica gel slurry, and montmorillonite colloidal solution in the mixture is 1:0.5 - 2:0.5 - 2.

6. The preparation method according to claim 1, characterized in that: In step S6, the ammonia gas is generated by the volatilization of concentrated ammonia water under closed conditions, the concentration of ammonia water is 1 - 14 mol / L; the aging time is 2 - 8 hours.

7. The preparation method according to claim 1, wherein In step S7, the immersion time is 6 - 8h, and the organic solvent is absolute ethanol or methanol or acetone solution.

8. The preparation method according to claim 1, wherein In step S8, the drying method is supercritical carbon dioxide drying or supercritical ethanol drying.

9. Application of 3D printed silica composite aerogel component, characterized in that: The 3D printed silica composite aerogel component is used as a thermal insulation material.

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